The present invention relates to a disc reproducing apparatus wherein a disc is inserted into the apparatus by inserting a casing housing the disc therein. The loaded disc may then be removed from the apparatus by inserting the empty casing within the apparatus.
Generally, in a disc reproducing apparatus of this type, a disc, such as a video disc, is placed on a turntable, and information recorded on the video disc is reproduced by bringing a reproducing stylus in contact with the video disc. The information includes video signals and audio signals, and is recorded with very high density according to a PCM (pulse code modulation) recording system. If any foreign matter, such as dust or dirt, sticks to the video disc, therefore, reproduced pictures will be subject to noise. Accordingly, there have been developed various apparatus which enable an operator to set on and remove the video disc from the turntable without directly touching the disc.
Prior to being placed in the turntable, the video disc is housed in a casing opening at one side while it is surrounded by a retaining frame which is locked to the casing. In this state, the video disc is inserted into the reproducing apparatus through one side thereof. When the insertion is completed, the video disc together with the retaining frame, is held within the reproducing apparatus, and the retaining frame is unlocked from the casing. When the casing is drawn out of the reproducing apparatus, both the video disc and the retaining frame are removed from the casing through one side thereof and remain in the reproducing apparatus, so that the casing is emptied. In this state, reproducing operation is started. If the empty casing is inserted into the reproducing apparatus through the one side thereof after the reproducing operation is finished, the video disc, together with the retaining frame, is put into the casing through the one side thereof, and the retaining frame is locked to the casing. Then, if the casing is drawn out of the reproducing apparatus, the video disc and the retaining frame are taken out of the apparatus while they are contained in the casing.
In a disc reproducing apparatus of this type, the cartridge is generally forwarded from the start position in accordance with the rotation of the disc by the driving force of a motor and it is also reversed to the start position by the motor driving force. The reverse movement of the cartridge with this method is time-consuming and immediate reproduction of the next disc or the opposite surface of the same disc may not begin until the cartridge returns to the start position. Immediate reproduction from another disc or the other surface of the same disc may however be accomplished if two motors are incorporated into the apparatus each for driving the cartridge in the forward and backward directions, respectively independently of each other. The functions of the two motor system may alternatively be performed by the use of a reversible motor and a reduction gear mechanism for changing the transmission ratio according to the direction of rotation of the reversible motor. With this arrangement, according to the direction of rotation of the reversible motor, the speeds of the cartridge in the forward and backward directions are different from each other. However, these arrangements result in a complex configuration and high cost of the overall apparatus. Moreover, troubles tend to occur more frequently.
Even if the cartridge can be returned to the start position at high speed by the motor, the cartridge bounces at the start position due to such high-speed movement. This results in deviation of the cartridge position from the start position which causes damage to the stylus or tracking error. For this reason, a holding means for holding the cartridge upon its return movement must be incorporated. The holding means may securely hold the cartridge in position. However, the holding force of the holding means acts as a load on the motor and thus, a high-output motor must be used.